


Theatre of Competition

by PineByPine (Tyrannosaurus_Sex)



Series: Three Saplings (A Triplets AU Series) [3]
Category: Gravity Falls
Genre: Aged-Up Character(s), Multi, Threesome - F/F/M, Triplets
Language: English
Status: Completed
Published: 2019-07-05
Updated: 2019-07-05
Packaged: 2020-06-11 18:47:38
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,836
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/19546384
Author URL: https://archiveofourown.org/users/Tyrannosaurus_Sex/pseuds/PineByPine
Summary: Bored by Dipper's choice of movie, Ty and Mabel find other ways to amuse themselves.





	Theatre of Competition

Since Dipper insisted on seeing the movie he bought the tickets, but since Ty and Mabel were the ones with the sugar cravings they bought the snacks. The triplets sat in the back row of the theater so they could push up the armrests between their seats and get a little cuddly. The girls maneuvered Dipper into the middle and each grabbed a hand, intertwining their fingers and laying their heads on his shoulders. The first twenty minutes of the movie passed pretty pleasantly for Dipper, until Ty broke the silence.

"I'm bored. Mabel, aren't you bored?"

"Oh god yes." Her sister opined. "This movie is the snoozeville."

Dipper felt offended. "Hey it’s got dragons and sword fights and junk."

Mabel stuck her tongue out and made a raspberry noise. "The trailer does but so far its been wall to wall talking."

“It’s obviously going to start…” Ty’s fingertip pressed to Dippers lips, effectively interrupting him.

“While Dipper gets to enjoy his boring movie, I would like to propose an activity that will also keep the two of us entertained.”

“Do go on, dear sister. I’m all ears.”

“Well, you know how-” Ty made a conspiratorial throat clearing noise, “loud Dipper gets.”

Mabel giggled and nodded. They had recently been forced to enact a very strict never-when-the-parents-are-home-no-not-even-if-we-think-we-can-keep-it-under-control rule on account of Dipper’s volume and his apparent complete inability to control said volume when suitably stimulated.

“I propose that you and I enter into a good-natured bet. First one to make Dipper make an embarrassing noise wins.”

Mabel’s grin shone in the reflected light of the movie screen. “Usual stakes?”

Ty shrugged. “Sounds good to me. Would you like to set any ground rules or does a free for all sound good to you?”

Mabel tapped her chin with one finger and looked at the subject of their little competition. Dipper was wild-eye and probably about to break into a sweat. “No tickling. No biting. No under the clothing.”

Ty’s eyebrows rose. “Well if that’s how it’s going to be then we better make sure the playing field is set up properly.” She reached over, grabbed the zipper pull on Dipper’s hooded sweatshirt, and pulled it all the way down.

Dipper gulped nervously. He had just realized that neither one of them were releasing their grips on his hands. “Uh girls. Don’t I get some say in this?”

Mabel shot him a glance and patted his shoulder. “Shh, Dipper. Grownups are talking. Are we playing until the end of the movie?”

“Yep. Terms accepted?” She offered her free hand and they shook on it.

“For crying out loud,” Dipper grumbled, “you are five and ten minutes older than me and I just want to watch the damned movie.”

Ty leaned in and placed a lingering kiss on the corner of her brother’s jawline and felt him clench his jaw muscles in response. “It’s so cute when you think you get a say in these things.”

Mabel placed a hand flat against his chest and let out a little giggle. “My my, somebody is all a pitter patter.”

“Because what you two are proposing is likely as hell to get us caught.”

Ty scanned the movie theater. It was a Tuesday afternoon in the middle of summer. Apparently everyone else had read the reviews for this movie and had decided to pass on it. There were three other groups of patrons; a couple of women in the middle row, a group of three indistinguishable people farther forward, and, closest to the triplets, a man who was obviously asleep a few rows in front and far off to one side, his head limply flopped backward over his seat, mouth agape..

“I think we’ll be OK, scaredy-cat. You just enjoy your boring movie and Mabel and I will enjoy our game.”

It took about four minutes before Dipper had to actually bite the inside of his lip to keep from letting a moan escape his mouth. Mabel noticed this and paused in her light touches, catching Ty’s eye meaningfully. Which was when Dipper realized that while they were ostensibly “playing” against each other, they were going to drag this out for as much of the whole two remaining hours as they could. When one of them won, they no longer got to have their fun.

They let him cool off for about five minutes, but it seemed like only seconds after they resumed that rivulets of sweat were running down Dipper’s back, despite how cold the air conditioning was making it in here. He was straining with all his effort to keep his trap shut; the fear of the disastrous consequences of them being found out by someone giving him extra reserves of willpower.

“Hey, we said no biting.”

“I was nibbling, not biting.”

“Don’t push the line, Pines, or I’ll take this to the next level.”

Ty snickered and ceased running her lips along Dipper’s neck. She leaned across his lap toward her sister, then made a quick “come here” motion, indicating as if she wished to whisper something to her. Mabel responded by leaning over as well and turning her head for her ear to be spoken in to surreptitiously. Ty made a quick glance to be sure Dipper was watching, and like he had a choice; they were inches away and right in front of his face. Then she reached up with her free hand and in one swift motion, she’d pulled Mabel’s face back round and drew her in for a deep, long kiss.

Dipper was about to explode. He was practically vibrating with tension in his seat, hands pinned in his sisters’ laps, unable to do anything to mitigate the situation. He was starting to worry that if he bit his lower lip any harder, he was going to actually draw blood. 

The girls took their time with the kiss but when they separated, and Mabel looked at the straining expression on Dipper’s face, she tut-tutted her sister. “If that had been the winning move, you so totally shouldn’t have been allowed to call it in your favor; team effort as it was.”

Ty attempted an innocent expression. “Never would have occurred to me to even try to claim victory is such a scenario. I was just feeling a little bad at how much attention we were lavishing dear Dipper and none on ourselves.” As she whispered her hand dropped casually to Dipper’s knee and he nearly bolted up out his seat.

“Look girls,” he spoke very carefully through gritted teeth, “I know you’re having fun and all but is there anything I can do to get you to just postpone all this until we’re, you know, alone? I’ll do your chores for a week. I’ll take you shopping. Anything.”

His sisters giggled in response and then they both snuggled up closer to him. Dipper was on the edge of breaking down.

“You said embarrassing noise, right?” He bargained. “How ‘bout this, then?” Dipper scrunched up his face, opened his mouse, and made the loudest and most convincing series of pig squeals either of his sisters had ever heard out of him; the man on the other side of the theater even woke up and looked around, apparently startled and confused. “There. Game over. Winner: Dipper Pines.” 

The girls had shifted back from him in surprised at his sudden porcine imitation. They looked around and saw that the few other watchers in the theater had all turned to look at them. Ty reached up with her free hand and gently smacked the side of Dipper’s head in reprimand.

“Seriously,” she shook her head in disapproval, “we can’t take you anywhere.”

“It was either that or you two get what you wanted and we all get kicked out of the theatre for- you know.”

Mabel rolled her eyes, released Dipper’s hand, and slumped into her seat. “You worry too much, bro. Besides, it’s not like you weren’t having fun too.” She pointed at her brother’s lap, which was having a serious tenting problem. Dipper swore under his breath and performed a quick tucking maneuver to at least reduce the problem.

Ty reached up and scruffed Dipper’s shaggy hair. “You don’t have to be such a spoil sport about it. We were just winding you up; we don’t want to get caught either. You’re just so much fun to tease.”

Dipper made a small huffing noise and pouted in his seat. “Well neither of you are the one going home with blue balls at the end of the night.”

“Oh poor Dipper’s little nuts.” Mabel reached over and patted him on the top of the head. “Why would you think we’d be so cruel to our little brother, Big D? Ty and I were gonna help you out.”

His other sister flung her arm around Dipper’s shoulders and and squeezed. “Of course; sisterly duty and all.”

Dipper’s brow furrowed. “But what about the never-when-the-parents-are-home-no-not-even-if-we-think-we-can-keep-it-under-control rule?”

“Oh, mom and dad aren’t home.” Mabel leaned on Dipper’s shoulder and he felt Ty’s hand start to play with her hair. “They have that dinner party for dad’s work; they’ll be out late.”

They silently watched the movie; the sword fighting bit had started up, but even Dipper’s heart wasn’t in it. After a few minutes, Ty felt Dipper’s hand on her leg; he gave her a gentle squeeze. She leaned over and kissed his cheek. “Look who’s not too reluctant to play now.”

“Actually this movie did turn out to be pretty lackluster and it’s not like I was able to pay much attention to the first part. So I’ve sort of lost the plot and…”

“Dipper Pines!” Mabel scolded in a whisper. “Are you proposing that we skip the end of the movie you so generously paid for?”

“Well…”

Ty snatched a hand of each of her siblings and leapt to her feet. “Oh thank god, I thought you were actually going to make us finish this awful thing.” She started dragging them toward the exit door. They were in the parking lot in record time and Mabel started to strip from sweater down to just her pony adorned T-shirt. 

“Jeez, it was getting hot in there.” She tossed the garment at her brother and turned to walk backward a couple of paces ahead of the other two. “Now, I think Dipper was very patient with us, Ty; so he definitely deserves a little something.”

Ty’s eyebrows raised. “You thinking of our patented Triple-Double-Trouble?”

Mabel shot her some finger guns. “Read my mind, Tee.” Then her smile grew playfully sly. “Plus that’ll pretty much hit the reset switch on our favorite brother here, and you and I can get back to our bet.” She winked at Ty.

“You are so on, Mabel Pines.”

“Um girls, I think you’re expecting a bit too…” And then Dipper did the math and decided that with a Triple-Double-Trouble and a whole evening with the house to themselves, he was probably getting a bargain.


End file.
